The US is likely to start growing over the next few quarters. But US households are likely to remain subdued, as they cope with high debt and the prospect of unemployment. As the fiscal stimulus wears off, and the massive buildup of US government debt limits spending, the world will look elsewhere for demand growth.

The obvious candidates are the emerging markets. But they would have to change strategy, from pushing exports to expanding domestic demand. For countries like China, this would bring a welcome rebalancing of growth, from red-hot coastal areas to more remote western provinces. It would reduce regional inequality and the accompanying political tensions.

But something more dramatic could happen in the longer run when emerging market demand grows. Today, over three-quarters of the value added in a $200 Apple iPod consists of services such as design, marketing, advertising and finance, which are provided by firms in developed countries that are close to today's consumer. Less than a quarter of the value added comes from the manufacturing and assembly, typically done in an emerging market. But when emerging market consumers account for a greater share of world spending, companies closer to them will be better able to anticipate their needs and innovate, design and market to their tastes.

In India, for example, Tata Motors has started producing a “people's car”, the Tata Nano, which is priced at $2,000. The Nano is aimed at India's growing middle class. This may seem surprising. In the US, middle-class families would like a safe vehicle in which to transport their children, typically a big, expensive minivan or SUV. A tiny cheap car would hardly be their idea of safety. Ratan Tata, chairman of Tata, however, wants to appeal to the desire for greater safety.

Today, the typical Indian middle-class household can only afford a motorcycle. The household travels precariously, with the husband driving, number one son seated astride the petrol tank, the wife sitting demurely behind holding the new-born baby in her arms, and number two son clinging on behind her. The Nano does not have a powerful engine, but this does not matter when top speeds are constrained by the crowded roads. The resulting lower price, and the fact that the entire family travels within closed doors, has made safety affordable. While you do not need to be Indian to understand the demand for such a car, it helps to have travelled the roads of a country like India and empathised with the needs of that family perched on the motorcycle.

Innovation and services like marketing and advertising will be driven by corporate managers who are closer to the consumer, if not physically, then mentally. This will be an enormous advantage for companies with a significant presence in emerging markets. They can take innovations across borders to other, similar emerging markets, increasing intra-emerging market trade. If all goes smoothly, these companies will account for a much greater portion of the world's innovation and value-added services, increasing emerging market prosperity. Rich countries will gain too as markets expand.

Emerging markets still have much to do. For the shift in demand to take place smoothly, they have to allow their currencies to appreciate. A collective commitment, especially in Asia, not to intervene in currencies except during extreme volatility would smooth adjustment. Hopefully, China will allow the renminbi to reach its true value in the interest of making it a reserve currency, and so support such a commitment.

Emerging markets also have to create the human capital to provide value-added services. This is happening: China is building world-class universities while Chile is outsourcing higher education, offering scholarships to all students who win places at top foreign universities.

Finally, emerging markets must proceed with care; export-led growth has stabilised their finances and built foreign exchange reserves. A focus on domestic demand carries with it the danger of excess, of runaway government deficits and credit-fuelled growth. As the US has shown, domestic demand-led growth is not easy to manage. The crisis may have brought forward the possibility of the age of the emerging markets. They have to make it a reality.

The author is a professor at the Booth School at the University of Chicago and a former chief economist of the IMF